This is the second part of installing Exchange Server 2007 with Service Pack 1 on Windows Server 2008.
You can see the scenario and the required features and server roles here: Installing Exchange Server 2007 with Service Pack 1 on Windows Server 2008 - Part 1.

Pre-installation
Before you can start the installation you have to install the following components:
- .NET Framework 2.0
- Microsoft Management Console
- Microsoft Windows PowerShell
You can either install the PowerShell by using the command line or you can use the Server Manager to add the required PowerShell feature. If you want to use the command line run the following command:
ServerManagerCmd -i PowerShell
You can also use the Server Manager:
Finally we can start the installation of Exchange Server 2007.
Installation
Click next at the introduction screen.
You can then turn on or off the error reporting.

Choose the typical installation of Exchange Server.
If you have Outlook 2003 clients in your environment choose yes, if not choose no.

After that your system will be analyzed if all required features are installed.
If all required features are installed you shouldn't the the following screen with the red bullets.
If you get the error message "Setup cannot detect an SMTP or Send connector with an address space of '*'." you can refer to the following article: http://support.microsoft.com/kb/556055/en-us.

Now you can start the installation process.

After finishing the installation you have successfully installed Exchange Server 2007 in your environment.

Please not that this is not a best practice article on how to deploy Exchange Server in a production environment.